At the recent MySQL Tech Tour Events in New York and Boston I gave a presentation on MySQL integration with NoSQL,Big Data and the Cloud.
This covered discussion on topics including:
With the introduction of metadata locking in MySQL 5.5, it is much more
common to see queries stuck in the “Waiting for table metadata
lock” state.
If you see a query stuck in the “Waiting for table metadata lock”
state, waiting for a MyISAM table, then it is because this table
has been included as part of some uncommitted transaction
(whether intentionally or not).
In fact, it could be as simple as issuing SET AUTOCOMMIT=0
followed by a SELECT against a MyISAM table (a transaction can be
started 3 ways: START TRANSACTION, BEGIN, and SET AUTOCOMMIT=0).
After that, the table will be locked to other DDL statements
until the transaction is committed (or ended).
This metadata lock is meant for DDL statements, and so that is
what it blocks. However, once a DDL statement is blocked and
waiting, then all queries …
I am currently finishing some features to make a program highly
resilient to occasional crashing bugs. A particular function was
found to crash on queries of the form WHERE x
IN(NULL), and that crashed the entire program. Now we have
a framework for intelligently recovering from arbitrary crashes.
I will write more on this in the future, because I think it’s a
very interesting thing to share.
In this episode, I want to focus on a related topic: how do you test a program that is supposed to be resilient to bugs you can’t predict? Many new problems are caused by writing clever code that is supposed to detect, avoid, or recover from problems, even known problems. Unknown problems are even riskier.
The approach that has given me a great deal of confidence in the “resilience framework” is to write a “crash injection …
[Read more]Yesterday I wrote about what the diffstat between MySQL 5.5 and MariaDB 5.5 was, and previously to that, about the MariaDB code size as reported by sloccount. Let’s look at MySQL 5.6.
A naive wc based “lines of code” for MySQL 5.6 sql/ directory is ~490kLOC which contasts with MySQL 5.5 being ~375kLOC by the same measure. If we diffstat the sql/ directory like I did for MariaDB 5.5 we get:
357 files changed, 172871 insertions(+), 67922 deletions(-)
Versus, as you remember from yesterday for MariaDB 5.5 over MySQL 5.5:
250 files changed, 83639 insertions(+), 23090 deletions(-)
The MySQL 5.5 to 5.6 sql/ changes line up with What I found in my post …
[Read more]As we continue to test our Fractal Tree Indexing with MongoDB, I’ve been updating my benchmark infrastructure so I can compare performance, correctness, and resource utilization. Sysbench has long been a standard for testing MySQL performance, so I created a version that is compatible with MongoDB. You can grab my current version of Sysbench for MongoDB here.
So what exactly is Sysbench? According to the Sysbench
homepage, “Sysbench is a modular, cross-platform and
multi-threaded benchmark tool for evaluating OS [Operating
System] parameters that are important for a system running a
database under intensive
load.”
Get the most out of your use of MySQL Cluster by attending the MySQL Cluster training course. This three day course:
Register for a Private Happy Hour and Food Event at Sfuzzi Las Colinas, Irving, TX
Please join us for our MySQL tech event hosted by Oracle and learn more about the continued investment in the world’s most popular open source database. MySQL expert Benjamin Wood will be on hand to discuss new features, commercial extensions, and provide details on MySQL 5.6.
MySQL 5.6 Introduction
MySQL Commercial Extensions Review (HA, Back Up, Security,
Enterprise Monitor, Performance, Scalability)
Open Q&A
Monday, March 18, 2013
3:00 PM – 6:00 PM
Sfuzzi Las Colinas, Irving, TX
Sfuzzi Las Colinas
525 Meadow Creek Dr, Irving, TX, 75039
…
MySQL User Group meeting, Stockholm, Sweden - April 10,
2013
After some time the Swedish MySQL User Group is organizing and
announcing the upcoming MySQL User Group meeting in Stockholm!!!
Everyone who are around that area on April 10, 2013, please make
sure that you do not miss this great opportunity to listen and
ask questions the main guest Mats Kindahl, (the Senior Principal
Software Developer MySQL) who will be talking on Replication news
on MySQL 5.6.!!!
Above this main topic and Q&A on MySQL Replication, you will also have an opportunity to suggest topics for the upcoming SMUG meetings as well as enjoy the food & mingle.
Date: April 10, 2013
Start: at 4pm
Where (address) : Emineo; Lilla Västerbron 20; 11219 Stockholm;
Sweden
URL for registration & updates: LinkedIn; …
Galera Cluster for MySQL 5.5.29-23.7.3 has been released. This is a maintenance release with several important bug fixes. Downloads are available from our Launchpad download area: MySQL with Wsrep API 5.5.29-23.7.3 and Galera library 23.2.4.
This release includes RHEL/Centos 6 RPM binaries. The Galera library also introduces as experimental feature a preview from our Galera 3.x development work: weighted quorum calculation.
As usual, feedback and bug reports are welcome: Bug tracker, Mailing list.
[Read more]Catch the webinar: “Learn How MySQL 5.6 Makes Query Optimization Easier” for more tips on the 5.6 optimizer
While preparing the webinar I will deliver this Friday, I ran
into a quite interesting (although not very impacting) optimizer
issue: a “SELECT *” taking half the time to execute
than the same “SELECT one_indexed_column” query in
MySQL 5.6.10.
This turned into a really nice exercise for checking the performance and inner workings of one of the nicest features of the newer MySQL optimizer: the Index Condition Pushdown Optimization, or ICP, which …
[Read more]